Telephone



(No Model.)

T. A. EDISON.

TBLEHONE.

Patented Got. 17, 1882.'

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THOMAS A. EDISON, OF MENLO PARK, NEWT JERSEY.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 266,021, dated october17, 1882.

Application led October i7, 1881. (No model.) Patented in England June15, 1878, No. 2,396.

1o all whom it may concern Be it known that I, THOMAS ALVA EDISON, ofMenlo Park, in the State of New Jersey, have invented an Improvement inTelephones, (Gase No. 158%) ot' which the following is a specification.

This application is a division of my application No. 158, filed November11, 1878; andthe said division is made for the purpose of separatingfrom said original application matters that are notin interference, andfor separating the different features ot' invention into two additionalapplications. The present I term Case No. 158A. Letters Patent in GreatBritain, No. 2,396, show the present device. The same was applied forJune 15, 1878; but the specitication was not tiled until December13,1878.

The object of this invention is to transmit oral com municationsoverelectric circuits and said invention consists in devices fortransmitting positive and negative currents by varying the resistance inthe telephonie transmitter, in combinationwith a heatstone balance.

Thetransniitting-instrument,containingcarbon or similar material in thecircuit, is also peculiarly constructed, and the diai'ihragm of thercceiving-instrument is acted upon by an indnctorium.

In the drawings, Figure l represents the transmittirig-instrumentsectionally, and also shows the circuit -connections by a diagram. Fig.2 represents the circuit-connections in a slightly-moditied form, andFig. 3 is asection in larger size through thescI-ew andcircuitregulator.

The transmitting-instrument A contains the mouth-piece b and adiaphragm, lc, secured at its edges. The center ofthe diaphragm isplatinized, and upon this rests a button, c, of linely-dividedconducting material, such as inetallized charcoal, lamp-black, or iodideof copper. The metallic plate d is kept in contact with the button bythe spring c, and e is an adjusting-screw to regulate the pressure ofthe spring against the plate l and button c. Said screw passes throughthe metallic support that is secured to the vulcanite ring g around thebutton c. The rod thatis attached to the plate d passes freely into auaxial hole in the screw c', so as to be guided thereby, but allow thescrew to be set up to regulate the spring without thescrewactingdircctly 011 the plate d. The diaphragm is connected to thewire 4 and the plated to the wire 5. The button, of carbon or othersimilar material, bccomes a circuitregulating device to control theelectric condition of theline and cause the same to vary in amannercorrespondingtothe sound-waves that act upon the diaphragm, as setforth in applications heretofore made by me. The ring g andcircuit-regulatingdevices are upon the diaphragm It', and hence movewith it; but any atmospheric vibrations acting on the diaphragm 7cproduce a variation in the resistance ofthe carbon or similar button, c,in the electric circuit, in consequence ofthe difference in 'pressureupon such carbon button,resulting from the tremulous movement of 7o theparts and the inertia of the plate d. The carbon or similar material andthe metallic surfaces in contact therewith become the electrodes oftheelectric circuit. The transmitter A isin one branch of the Wheatstonebridge,

R3 being a resistance equal to that ofA when f not subjected to sonorousvibrations. It and E2 form the other sides of the balance and have equalresistances. The bridge-wire from M to N is contained in the electriccircuit that extends from N by the line wire to thc distant receiver H,thence to the earth, and returning to the earth-plate at thetransmitting-station and to M. The battery B, of several' cells, isbetween 5 and It 1?. When the resistance ot'A R2 is equal to that of ItR3 no current circulates upon the line. When sono rous vibrations varythcresistance ofthe carbon button c in A the current will pass upon theline in one direction or the other. When `the resistance of A isincreased the current passes in one direction. Then it is lessened thecurrent passes in the other direction in consequence of the balancebeing disturbed. The induction-coil H has its secondary coil included inthe line-circuit, and the primary coil is connected with atransmitting-instrument, T, constructed and operating in a similarmanner to thetransmitter A, the local battery B being in the circuitthrough the carbon button and primary coil. The receivinginstrument L isprovided with a diaphragm,

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that is acted upon by the core ot the inductioncoil H, and hence theinduction-coilis utilized,

. and serves for receiving or transmitting telephonically.

In Fig. 2 the balance of the similar batteries, B B', with oppositepoles to line,=is obtained by the rheostat R3, that is ot' a resistanceequal to that ot the instrument A-When at rest, and when the resistanceof the carbon button in A is increased or decreased by the sonorousvibrations the current will pass upon the line, either positiveornegative, according to the resistance in A.

In my application No.130 the diaphragm is in direct contact with asurface of plumbago or similar material, and in my application No.

`151, patented April 30, 1878, No. 203,016, a

v n e ies, a system of balanced circuits, a telephonie transmitterconstituting a variable resistance in one of the balanced circuits,andatelephonie receiver in the bridge-Wire of the balance, substantiailyV asset forth.

3. The combination, in a telephone, ofcarbon or similar material,formingacircuit-regulator, a diaphragm, and a holder upon and entirelysupported by the diaphragm, and arranged to resist the movement ot' thediaphragm and circuit-regulator, substantially as set forth.

4. Inaspeaking-telephone, thecoinbination, with the diaphragm, ot'earbonor equivalent material in the electric circuit, and a spring or yieldingpresser to apply an initial pressure to the carbon, and means forsupporting both the carbon and presser upon the diaphragm, substantiallyas set forth.

5. In a speaking-telephone, the combination, with the diaphragm, ot'carbon or similar material, a spring pressing upon the carbon, and

means for adjusting the pressure and supports therefor upon thediaphragm, substantially as Set forth.

Signed by me this 7th day of September, A. D. 1881.

THOMAS A. EDISON.

Witnesses:

GEO. T PINCKNEY, HAROLD SERRELL.

